Over its run, countless heroes and villains have come and gone from Agents of S.H.I.E.L.D., some currently MIA and many others losing their lives along the way, never to be seen again. As the show marches towards the final arc of its fourth season - the Agents of HYDRA arc - the time is ripe for many familiar faces from the past to resurface thanks to the existence of the Framework.
The alternate reality of the Framework gives the series the opportunity to bring back any number of long-lost fan favorites from the show's history, from some of the team's most dangerous enemies to many of their fallen allies. With a fifth season still not a surefire thing, allowing these characters to have one last ride in the alternate reality would be a great, fun way to honor their place in the series. That's not to mention all the loose ends still waiting to be tied up in the real world in regards to still-living characters, whose statuses remain unknown.
Putting aside missing characters from the current season that we'll likely see again before it's over, like Ghost Rider, let's take a spoiler-filled look back over the first three seasons to sort out which characters deserve a Framework-related resurrection or a long overdue reemergence in the present day just in case this is the show's final run.